长期施肥对黄土高原典型草原群落稳定性的影响及机制研究

施肥是当前草地生态系统最常见的人为干扰方式之一,可导致草地生物多样性和生态系统稳定性发生显著变化.该研究以黄土高原典型草原为研究对象,通过连续8年的氮肥(尿素)野外添加试验,分析不同氮肥处理(分别为0、5、10、20、40和80 g·m-2)对草地群落稳定性的影响,并分析检验可能影响群落稳定性的四个潜在机制(物种多样性...     

Vitellogenin’s putative role in <Emphasis Type="Italic">Tegillarca granosa</Emphasis>’s cadmium detoxification

The bloody clam, Tegillarca granosa, is a commercial benthic bivalve, having a strong accumulation ability and torrelence to cadmium. To investigate whether vitellogenin (Vg) is involved in cadmium (Cd) detoxification, the full-length cDNA of T. granosa Vg was cloned, and its expression pattern in response to cadmium exposure was studied compared with the reference metallothionein (MT) gene. The full T. granosa Vg sequence consisted of 8988 bp, including a 6930-bp open reading frame that encoded a 2309 amino acid polypeptide. The deduced Vg protein contained a Vg N-terminal domain, domain of unknown function (DUF1943), SbcC domain, and von Willebrand factor type D domain (VWD). Multiple metal-binding sites were predicted in the deduced T. granosa Vg protein, suggesting its potential in functioning as a metal-binding protein. In addition, Vg expression increased in the T. granosa digestive gland and hemolymph in time-dependent manner after exposure to 1, 3, 6 and 9 μg/L Cd for 28 days. MT expression was measured in parallel with Vg expression, and the latter was more sensitive to Cd induction than the former. Together, results of the present research suggested that Vg may play an important role in T. granosa metal detoxification.     

人卵巢浆液性囊腺癌永生化细胞系BUPH∶OVCA-3的建立及其生物学特性

介绍人卵巢浆液性囊腺癌永生化细胞系的建立 ,研究其生物学特性 .以卵巢浆液性乳头状囊腺癌的腹水细胞为材料 ,进行体外培养 .将永生化基因———SV4 0T抗原基因转染第 2代细胞 ,得到永生化细胞系 .通过光学显微镜、生长曲线测定、染色体分析、双层软琼脂培养、裸鼠接种、免疫组化等 ,研究其生物学特性 ,并与其来源细胞的生物学特性进行比较 .建立了一株人卵巢浆液性囊腺癌永生化细胞系 ,命名为BUPH∶OVCA 3,现已传至 6 0余代 .其生物学特性为 ,细胞生长旺盛 ;具有人体恶性细胞的核型特征 ;细胞恶性度较低 ,不具有集落形成能力及裸鼠接种致瘤性 ;除较未永生化细胞生长速率增快 ,饱和密度增加外 ,仍保留上皮细胞的分化表型 .结果表明 ,BUPH∶OVCA 3为一株恶性度较低的人卵巢浆液性囊腺癌永生化细胞系 ,保留其来源细胞的生物学特性 ,可作为研究恶性度较低的卵巢上皮癌的体外模型     

辽宁省食源性副溶血性弧菌毒力基因、血清分型及耐药性分析

研究辽宁省2017-2020年市售水产品及其制品中分离的158株副溶血性弧菌的毒力基因、血清分型和耐药性, 为食源性疾病的暴发和散发进行评估和预警。

采用多重荧光定量PCR技术对毒力基因tlh、tdh和trh进行检测, 同时检测血清分型; 采用肉汤稀释法测定副溶血性弧菌MIC值并分析其耐药性。

158株副溶血性弧菌中均携带tlh基因, 携带tdh基因的菌株2株, 携带trh基因的菌株2株, 同时携带tdh基因和trh基因的菌株1株; 158株中67株血清型为O2(含K不分型), 39株为O3(含K不分型), 携带tdh和trh毒力基因的菌株血清型均为O3;副溶血性弧菌122株(77.22%)对头孢唑啉耐药, 36株(22.78%)对头孢西丁耐药, 30株(18.99%)对氨苄西林耐药, 18株菌呈现耐受2类及以上的多重耐药性。携带毒力基因的5株副溶血性弧菌对头孢唑啉均耐药。

大多数食源性副溶血性弧菌不携带毒力基因, O2血清型(42.41%)是辽宁省食源性副溶血性弧菌的主要血清型, 其次为O3(24.68%); 副溶血性弧菌对头孢唑啉显著耐药, 少数菌表现出多重耐药, 提示应继续加强水产品及其生食制品中副溶血性弧菌的致病性和耐药性监测。

     

Negative HBcAg in immunohistochemistry assay of liver biopsy is a predictive factor for the treatment of patients with nucleos(t)ide analogue therapy

The hepatitis B core antigen (HBcAg) is an important target for antiviral response in chronic hepatitis B (CHB) patients. However, the correlation between HBcAg in the hepatocyte nucleus and nucleos(t)ide analogue (NA) therapeutic response is unclear. We sought to evaluate the role of HBcAg by analysing liver biopsies for viral response in NA‐naïve hepatitis B e antigen (HBeAg) positive (+) CHB patients via immunohistochemistry (IHC). A total of 48 HBcAg‐negative (?) patients and 48 HBcAg (+) patients with matching baseline characteristics were retrospectively analysed for up to 288 weeks. Virological response (VR) rates of patients in the HBcAg (?) group were significantly higher at week 48 and 96 than the HBcAg (+) group (77.1% versus 45.8% at week 48, respectively, P = 0.002 and 95.3% versus 83.3% at week 96, respectively, P = 0.045). The serological negative conversion rate of HBeAg was significantly higher in the HBcAg (?) than in the HBcAg (+) group from week 96 to 288 (35.4 % versus 14.6% at week 96, respectively, P = 0.018; 60.4% versus 14.6%, respectively, P < 0.001 at week 144; 72.9% versus 35.4%, respectively, P < 0.001 at week 288). The cumulative frequencies of VR and lack of HBeAg were higher in the HBcAg (?) group (both P < 0.05). Binary logistic regression analysis showed that HBcAg (?) was the predictor for the lack of HBeAg (OR 4.482, 95% CI: 1.58–12.68). In summary, the absence of HBcAg in the hepatocyte nucleus could be an independent predictor for HBeAg seroconversion rates during NA‐naïve treatment in HBeAg (+) CHB patients.     

Responses of litter decomposition and nutrient release rate to water and nitrogen addition differed among three plant species dominated in a semi-arid grassland

Background and aims

Precipitation and nitrogen (N) deposition are predicted to increase in northern China. The present paper aimed to better understand how different dominant species in semi-arid grasslands in this region vary in their litter decomposition and nutrient release responses to increases in precipitation and N deposition.

Methods

Above-ground litter of three dominant species (two grasses, Agropyron cristatum and Stipa krylovii, and one forb, Artemisia frigida) was collected from areas without experimental treatments in a semi-arid grassland in Inner Mongolia. Litter decomposition was studied over three years to determine the effects of water and N addition on litter decomposition rate and nutrient dynamics.

Results

Litter mass loss and nutrient release were faster for the forb species than for the two grasses during decomposition. Both water and N addition increased litter mass loss of the grass A. cristatum, while the treatments showed no impacts on that of the forb A. frigida. Supplemental N had time-dependent, positive effects on litter mass loss of the grass S. krylovii. During the three-year decomposition study, the release of N from litter was inhibited by N addition for the three species, and it was promoted by water addition for the two grasses. Across all treatments, N and potassium (K) were released from the litter of all three species, whereas calcium (Ca) was accumulated. Phosphorus (P) and magnesium (Mg) were released from the forb litter but accumulated in the grass litter after three years of decomposition.

Conclusions

Our findings revealed that the litter decomposition response to water and N supplementation differed among dominant plant species in a semi-arid grassland, indicating that changes in dominant plant species induced by projected increases in precipitation and N deposition are likely to affect litter decomposition, nutrient cycling, and further biogeochemical cycles in this grassland. The asynchronous nutrient release of different species’ litter found in the present study highlights the complexity of nutrient replenishment from litter decomposition in the temperate steppe under scenarios of enhancing precipitation and N deposition.

     

大蒜中期染色体内的核糖核蛋白物质

研究了大蒜（Ａｌｌｉｕｍ ｓａｔｉｖｕｍ Ｌ．）中期染色体的超微结构和ＲＮＰ物质。常规染色表明,大部分染色体内部有低电子密度区,有的染色体中低电子密度区域较大而似孔洞。银染结果也证明了有大小不等的孔洞存在。Ｂｅｒｎｈａｒｄ 染色显示,在染色体周边和染色体内部都有ＲＮＰ分布。用ＮａＯＨ 处理证明了Ｂｅｒｎｈａｒｄ 染色法所显示的深染区确实含有ＲＮＡ。ＲＮＰ量的多少与ＥＤＴＡ 的分化时间呈负相关     

Embryological Observation on the Apomictic Rice-ApⅢ (Shuang 13)

Since 1988s, the phenomenon of multiple seedlings and multiple embryoes of apomictic rice, Ap Ⅲ (Shuang 13) has been interestingly concerned. Embryological investigation of Ap Ⅲ has been carried out with the whole dissection and conventional sectioning technique. The main conclusions are as follows: 1.8. 9 % of 5000 matured caryopsises, contained one embryo in a caryopsis, from which single seedling arose, while 8.9 % twin embryoes and 1.2 % triplet embryoes of which developed two seedlings and triple seedlings respectively; 2. In over 700 young caryopsises, 90.0%～95.0% contained only one embryo, 5.0%～7.0% twin embryoes, except a few of the ovules with absorptive embryo sac or embryo and endosperm. Triplet embryoes caryopsis could not be traced further due to their low frequency; 3. Authors' materials showed that all the single, twin and triplet embryoes were situated at the micropylar end in one embryo sac of young ovule and no adventitious embryo was seen outside the embryo sac of ovules. From the aforementioned results, it can be infered that albeit single embryo is derived from the egg cell yet it could be possible twin or triplet embryocs may be developed from the egg cell and one or two of the synergids either or not through fertilization.